Thinking, Fast and Slow

rational, and their thinking is normally sound. Second, emotions such as
fear, affection, and hatred explain most of the occasions on which people
depart from rationality. Our article challenged both assumptions without
discussing them directly. We documented systematic errors in the thinking
of normal people, and we traced these errors to the design of the
machinery of cognition rather than to the corruption of thought by emotion.
Our article attracted much more attention than we had expected, and it
remains one of the most highly cited works in social science (more than
three hundred scholarly articles referred to it in 2010 ). Scholars in other
disciplines found it useful, and the ideas of heuristics and biases have
been used productively in many fields, including medical diagnosis, legal
judgment, intelligence analysis, philosophy, finance, statistics, and military
strategy.
For example, students of policy have noted that the availability heuristic
helps explain why some issues are highly salient in the public’s mind while
others are neglected. People tend to assess the relative importance of
issues by the ease with which they are retrieved from memory—and this is
largely determined by the extent of coverage in the media. Frequently
mentioned topics populate the mind even as others slip away from
awareness. In turn, what the media choose to report corresponds to their
view of what is currently on the public’s mind. It is no accident that
authoritarian regimes exert substantial pressure on independent media.
Because public interest is most easily aroused by dramatic events and by
celebrities, media feeding frenzies are common. For several weeks after
Michael Jackson’s death, for example, it was virtually impossible to find a
television channel reporting on another topic. In contrast, there is little
coverage of critical but unexciting issues that provide less drama, such as
declining educational standards or overinvestment of medical resources in
the last year of life. (As I write this, I notice that my choice of “little-covered”
examples was guided by availability. The topics I chose as examples are
mentioned often; equally important issues that are less available did not
come to my mind.)
We did not fully realize it at the time, but a key reason for the broad
appeal of “heuristics and biases” outside psychology was an incidental
feature of our work: we almost always included in our articles the full text of
the questions we had asked ourselves and our respondents. These
questions served as demonstrations for the reader, allowing him to
recognize how his own thinking was tripped up by cognitive biases. I hope
you had such an experience as you read the question about Steve the
librarian, which was intended to help you appreciate the power of
resemblance as a cue to probability and to see how easy it is to ignore
relevant statistical facts.